1. Field of the Invention
The present invention relates to 1,3-pentadiene derivatives and an electrophotographic photoconductor which comprises a photoconductive layer comprising at least one of the 1,3-pentadiene derivatives.
2. Discussion of Background
Some examples of photoconductive materials for use in the conventional photoconductors used in electrophotography include inorganic materials such as selenium, cadmium sulfide and zinc oxide. In an electrophotographic process, a photoconductor is first exposed to corona discharge in the dark, so that the surface of the photoconductor is electrically charged in a uniform manner. The thus uniformly charged photoconductor is then exposed to original light images and the exposed portions selectively become electroconductive, causing the dissipation of electric charges from these portions of the photoconductor. Latent electrostatic images, corresponding to the original light images, are thus formed on the surface of the photoconductor. The latent electrostatic images are then developed by a so-called "toner" which comprises a colorant, such as a dye or a pigment, and a binder agent made of a polymeric material. Through this process, visible, developed images can be obtained on the photoconductor.
The fundamental requirements of a photoconductor for use in electrophotography are: (1) chargeability to a predetermined potential in the dark; (2) minimal electric charge dissipation in the dark; and (3) rapid dissipation of electric charges upon exposure to light.
While the above-mentioned inorganic photoconductive materials have many advantages over other conventional photoconductive materials, they also have several drawbacks. For example, the selenium photoconductor, which is widely used at present and sufficiently meets the above-mentioned requirements (1) to (3), is also characterized by difficult methods which ultimately result in increased production costs. The properties of the material itself are less than desirable. Its low flexibility hinders the process of forming it into a belt. As well, its vulnerability to thermal and mechanical shocks necessitates extremely careful material handling.
Cadmium sulfide photoconductors and zinc oxide photoconductors are prepared by dispersing cadmium sulfide or zinc oxide in a binder resin. Due to this dispersive condition, the mechanical properties of the resulting material are poor such as surface smoothness, hardness, tensile strength and wear resistance. Thus these materials are not suitable for use as photoconductors where much repetition is encountered, such as in plain paper copiers.
Recently, varieties of organic electrophotographic photoconductors have been proposed to cover the shortcomings of the inorganic photoconductor. Some of them are now being used in practice. Representative examples of the organic electrophotographic photoconductor include one that is comprised of poly-N-vinylcarbazole and 2,4,7-trinitrofluorene-9-on U.S. Pat. No. 3,484,237), a photoconductor in which poly-N-vinylcarbazole is sensitized by a pyrylium salt type dyestuff (Japanese Patent Publication 48-25658), a photoconductor containing a main component of organic pigment (Japanese Laid-Open Patent Application 47-37543), and a photoconductor containing as the main component, an eutectic crystalline complex made of a dye and a resin (Japanese Laid-Open Patent Application 47-10735).
Although the above-mentioned organic electrophotographic photoconductors have many superior in many respects to other conventional photoconductors, they do not satisfy all the requirements of an electrophotographic photoconductor.